Radio transmitter



Jan. 16, 1951 T. H. PRICE Y RADIO TRANSMTTER Filed June 27, 1947 ,wa/a Paf-quemar aar/a7- ya. vc v! va v6 Patented Jan. 16, 195.1 Y

RADIO Y'rRANsMi'r'rElit `Thomas Henry Price, Chelmsford, England, as-

signor, by mesne assignments, to Radio Corporation of America, New York, N. Y., a cor-` poration of Delaware I' Application Jlnem, 1947,' serial No. 757,609

. In Great Britain April 17, 1946 section 1, Public L'aw 69o, 'August s, 1946 l v Patent expires April 17, 1966 This invention relates the so.called phase-swing type, and provides an improvement in or modification of part 01"v the phase-swing radio-transmitter described and claimed in United .States Patent'iltZBLlBl, dated'August 7, 1945. 'l

l In the said patent, I have claimed a phase-v swing radio-frequency transmitter, Aincluding two similar valves or valve-stages to the grids of which in operation high or radio frequency voltages are applied in predetermined phase relationship and in which duringmodulation, the phase positions ofthe voltages are caused toswingwtowards and away from each other about the unmodulated position respectively for positiveand negative half-cycles of modulation'voltage,` the anode circuit of each' valve including a tuned circuit,` these tuned vcircuits being substantially similar to each other, and a power-absorbing device to which each tuned vcircuit is coupled by means of a quarter-wave impedance-inverting device or network, the arrangement being such that as a result of varying the said phase positions, the'iamplitude ofthe current deliveredto the power-absorbing device is 'substantiallylinearly varied. Y f

According Yto this invention, a phase-swing` radio-'transmitter includes a source of radio-frequency energy, 'a first and a second pair of therinicnic valves, means including a tuned input sourceto a control grid ofcircuit 'coupling lsaid all the valves so that ythe grid ci a valve of each to radio-.transmitters of 7 claims. y, (ci. vS32-fai) justable so that each valve of the secondpairi contributes A.the saine amount of radio-frequenc'yfI energy to their common anode tuned circuit, and.`

a* source of modulation potentials for dineren-itlally varyingsaid direct bias potential.

The two reactive coupling circuits may coin-... prise capacitors, each of whichin conjunction. with the common tuned anode circuit for the sec-il ond pair of valves and the individual tuned cir. cuit of one o f the Valves of .the rs-tpairconstitutes a quarter wave 'coupling circuit. .In stead of capacitors, inductors maybe used, D. blockingcondensers being included. 7 J Q,

The valves oftherst pair, and the valvesfof. the second pairvmaydbe pentodes,.with the radio-"i frequency energy applied to the firstl or inner., grid in each valve of each pair, the bias potentials', for the valves of the second pair-being'applied tofJ their third or outer grids.

pair is energised in anti-phase with the grid of the other valve of thesarne pair, individual par-' allel tuned anode circuits for .the Valves or" the' first pair and a common parallel tuned anode circuit furthe' valves'of the second pain'an output connection for each Valve of the'rst pair, A:means for controlling the amount ci radio-frequency energy each valve of the second pair contributes to the common tuned anode circuit, a pair of ree active coupling circuits each connecting the common tuned anode circuit to a different valve of the first pair the whole arrangement being such that the phases oi resultant radio-frequency enf, ergies which appear in .the two output connec tions swing about their phase positions towards and away from each other in response to dinerential variation of the amount of radio-frequency energy the valves o the second pair contribute to the common tuned circuit. y The means for controlling the amount of radiofrequency 'energ pair contributes cuit mayA include. a source of dllt potentiel., ad-

y which A each vvalve of Athe second. to the common tuned` anode cir The invention is illustrated in the drawing in.

' which Fig.r1,irllustrates by circuit element andiy circuitl element connection a modulator arranged in accordance with my invention and, Y Y. y

Fig. 2 illustrates vby vector diagram the mode: ofoperation of the modulator of Fig. 1. fl Fig. 1 shows a pair of valves VlV and V2, the'. rst pair abovereferred to, each of whichis a. pentode vand each of which is provided 'with a. tuned anode circuit, respectively TCI andl TG2.A A common tuned grid circuit TCg is provided..l for these valves and is coupled, Yby means: of a. transformer T,Ato a source of radio-frequency. energy, not shown Y. but indicated at The. secondary winding of tuned grid circuit 'ICg con-i stitutes the inductive element of the tuned` gridcircuit, opposite ends of which are connected re`- spectivelyrto grids gi of valves Vll and V2. The mid-point of the tuned grid circuit is connected to earth as indicatedvat E. HGrids g2 and g3 off valve Vl and V2 are connected in conventional.

ymanner, vto suitable biases.` The tuned circuitsv are resonantfat thefrequency -of the radio-fre-V in anti-phase'as vindicated by' vectors 1J! and v2 in the vector diagram. Y The anode of valve Vl is connected througha condenser Cl to 'a point P and the anode of valve V2 is' connected vthrough a condenser C2 to point P. Thus, sincev the radio-frequency potentials at" these anodefs are in anti-phase, and assuming that condensers Ci and C2 have been chosenor of valves V3 and V4.

adjusted with due regard to their respective capacities, point P will be at Zero radio-frequency potential relative to:A the anodesot valvesJ Vi and. V2. v 1:.

.The circuit diagram also shows another pair of valves V3 and Ve, the Asecond pair above re, `v f ferred to, each of which is a pentode, these valves being provided with a common tuned anode cuit TC34. Opposite ends Qt the tuned. grid cuit TCg are connected respectively tof-gridsD gt. Grids-pf2; of; valves. and. V4 are connected, in conventional manner, to a source of bias potential, and .grids g3 are. connected to a source not shown but i-ndicatedA ait GB of adjustable bias potential, preferably so that the biases can be adjusted difterentiallyz.

By reason of the connections describediiorvalvesi V3 and V4, and assuming the biases on gridsgto these valves are such `having regard' to the parameters of thecircuit elerrients, that theA sysis balanced there will be no output" atpoint 13;. from valves V3 and V41. low-frequencyl potentialA from* a source of such, not' shown but indicated LFis superimposed: onbias GB so as differentially tol vary the biases.f applied; to grids' gri of valves V3i and, V4. This low frequency potential may represent signals such asl audioL or music signals. As the biases onA grids gli* of valves' V3 and4 W are diererrtially varied an output- Will. appear atvpoint' P, thisloutput' having' a phase which is deterrrrinedrl byl which Valve V3 or V' is' contributing themost radio-free quency energyrtoetuned' circuit TCM? and ann-ampflit'ude determined by; thel extent of uns-balance. produced by the l'owefreduency potentials; This? will" be in' phase Witli1 'Irl or 112' as, valVeV' or :is contributing the radio frequency energy to point P;

The electrical dimension of condenser CI:y is* suchi, having regard tothe electrical; diinensionsof tfutiedv circuits TCT and TCM, that these elements constitute a quarter-waveicoupling circuit' cou-f pling point Pto connection v1, and lsi-rrrilarlyfor'r condenser C2, regard to point P and connection o2- By' y reason olf the qua-rterhwave fia-ture of the coupling between pointv P and connections vl and' U2; the radiov frequency poten-Y tialsl appearing at point P, which at that point. are' in phase with either ol or v2?, -of the vector diagram and of a magnitude depending on the amplitude of the lowf-frequency potential-s, will appear at connections oland' v2 of the circuit diagramD as indicated by vectors v3 or v4, that' is phase quadrature `withi potenti-als ci and v2". ".Ehere will' thus be produced resul-tant potentials at the connectionsv and 122.' Thus, if condi-tionsof 'modulation are such that the radio-frequency potentials appearing atconnections vf and v2? from point P are represented by vector v3, vc' of:

course being absent, forv varying amplitudes of the potential v3 the phase and amplitude of thev resultant willhave one of an i-nnitude of Values; two of which areY represented by the pairs of?` vectors va and 11a i', and vb and obi. Similarly if vconditions of' inochilation are such that the radio frequency-potentials' appearing at connec tions o! and o2 from. point P are represented by vector mi, o3 being absent, ior varying ampli'- tudes of potential v4, the, phase and amplitude of the resultant will have one of an innitude of Y values, two of which are represented byk the pairs of vectors' ocfandvchandod and odi.

the amplitude of this low-frequency potential,

tion ofthe circuit arrangement would be effected.

. lit. coursier,` tra be understood, that if it were input'. electrodes or; the. d

desired taeiect the phase control at a relatively low powerlevel, conventional amplifying stages or cathode follower coupling stages could be interposed between the phase modulation circuit of the aoco'mpanying circuiti diagram: and?A power stage 6 Figure 11 off the; drawing accompanying the; Said patent:speci'cationl f It wi l-1 be apparent', that; since the, eiecii of' variation-.ofthe biases by; loro frequency sise nals LF applied to the third grids: oi? val es; and. WI is to. swing the. phases or? outputs; el and o2, phase positions: other' than anti-.phase may' be selected as1 the. normal; unmodulated, 'condition merely by: appropriate; adiu'stmenft or the Value oiGB.

Moreover, by a` simple. addition tu the ilflustrate infphase. amplitude; modulation QE outputs: oli and v2; maybe.. The .ztcllits addi-tion would bei required to ensure, that; as; the; output; or valve: v3 or VA predominantes, out put' or vf'lf andA v2; should. be reduced.. ln. the when the. outputsof. calves-Vfland hare disappearedf andi valve V3i 0 1? il-4;' 810.11m.- is, supply-f.j ing output-,the phaseor outputs cl ande willbe ask 1.1311 or of the; Vector diagram.. Thus;- the: phase change. of: at and r2.2: can bei made, ecp-at to. 9er.. 'Ene addition required to be, madeto the circuit-will' bey apparerrtto those skilled in the, artt.

Whatzisclai-med Y 1. In a modulation system, a rst pair of' elec-` 'tron`V discharge. devices: each having input electrodesv and hai/:ing output electrodes; inY individual parallel tuned radio frequencyV circuits.; a second pair off electron discharge. devices; hav/inemeans. iforV modulating, the ga off the de s. of the; second, pairY inl accordance; Sign-@1.33, a. separate. phase. displacing; rear/italic@ coupli'ng the. output. electrode; of' each. device of: the: Sel-3.011131- parir: tothe output:v electrode of a diflerent one of the. devices of' the; first pair, `and mea-ne for deriving; output: from the outputY electrodes of said` first.. pair of" devices. 2. In amodulation system;L a first pair 0i Slee.

' input; elsetron discharge devices each hay; A trodes and having output.v electrodes including an anode, a separate parallel tuned. circuit. coupled to each anode, a.- second; pair of electron discharge devices each having an anoclje,` aode andV a control electrode, a, source, of; alternate. ing current to be modulated' coupled dilerentiallyI to the input electrodes of;A the' devices; oftlfier'st pair of devicesY and diierentially to4 the cont-rol electrodes ofy the devices of the secondiy pairA .ofdevices, a tuned circuit coupling the anodes ofi the second pair of devices in parallel, a separate phase shifting network coupling the anode of each device of thesecond pair to the anode of a diierent one of the devices of the iirst pair, apparatus for applying substantially like base biasing potentials to corresponding electrodes in said second pair of devices, and connections for applying modulation differentially to corresponding electrodes in the devices of said second pair of devices.

3. A system as recited in claim 2 wherein each of said phase shifting networks includes said last named tuned circuit and a different one of said rst named tuned circuits.

4. A system as recited in claim 2 wherein said first corresponding electrodes are auxiliary control electrodes in said second pair of electron discharge devices.

5. A system as recited in claim 2 wherein said phase shifting networks have an electrical length substantially equal to one-quarter of the length of a Wave of the frequency to which said tuned circuits are tuned. Y

6. In a modulation system, asource of radiofrequency energy, a iirst and a second pair of electron discharge devices each having an anode, a control electrode and a cathode, means including a common tuned input circuit coupling said source directly to a control electrode of each one of the devices so that the control electrode of a 3o device of each pair is energized directly from said source anti-phasally with the control electrode of the other device of the same pair, separate parallel-tuned anode circuits for the devices of the rst pair of devices, a common parallel-tuned anode circuit for the devices of the second pair of devices, an output connection for each device .of the rst pair of devices, means for controlling the amount of radio-frequency energy each device o the second pair of devices contributes to the common tuned anode circuit, and a separate reactive circuit coupling the anode of ,each device of the second pair to the anode of a different one of the devices of the first pair.

7. A modulation system as dened inclaim 6, wherein the last-mentioned means includes a source of direct bias potential connected to corresponding electrodes in the second pair of devices, said potential being adjustable so that each device of the second pair contributes the same amount of radio-frequency energy to the common tuned anode circuit, and a source of modulation potentials for diierentially varying said direct bias potential.

THOMAS HENRY PRICE.

REFERENCES CITED UNITED STATES PATENTS Name Date Crosby July 22, 1941 Number 

